its not 5.5 hp . what happened to the bike . what was it on . that's one of my motors. look at the head or motor case are there any markings ? like a triple mmm or a double ss
? its a 49cc . it might be one with a ported head . does the muffler have a pipe coming out of it or just a hole on the side ?

here is one i am just finishing up . built this one from the ground up , every parts order i would get one or two pieces to the puzzle , motor case one time , head kit next time , until i have all the things needed to put it together , a few of the pieces are used , like the e start was used but cleaned up pretty good , i have also changed the hp air filter , to one without the rubber , this has the billet style air cleaner , i have noticed that with vibration the band clamp can cut through the rubber then the motor sucks the flakes in . to avoid that problem make sure the inside ridges on the rubber are seated in the matching ridges on the velocity stack then just lightly clamp the filter with the band , people crimp them on too tight , also very important make sure to fit the filter so no metal touches the velocity stack if the two vibrate against each other you will get metal flakes in your cylinder . if you can avoid those two problems that motor is a good motor . ,http://s480.photobucket.com/albums/rr161/thescooterguy/?action=view&current=kirnin065.jpg